JPS58150893A - Vent system supporting structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a downer for a nuclear reactor containment vessel! Regarding the support structure,
In particular, the present invention relates to a vent system support structure suitable for reducing the lateral vibration load applied to the downcomer and the screw 9 (swing mode) load applied to the vent header during steam condensation.

A conventional example is shown in FIG.

FIG. 1 shows a cross section of the wet well l of the Mark-Ill Fushi reactor containment vessel, and shows the vent %j4. Then there is the vent header 5 which runs horizontally through the wetwell airway section 2. Furthermore, a downcomer 6 extends into the pool water 3.

The downcomers 6 are installed in pairs 9 from the same position on the vent header 5, and their tips are connected to each other by bracing 7. Next, a ring gutter 8 is installed on the inner wall of the wet well 1.

Assuming a loss of coolant accident due to a rupture of the reactor's primary system piping, a mixture of air, water, and steam will first flow from the dry well into the vent pipe 4. The steam is released into the pool water 3 through the vent header 5° downcomer 6, and the steam is #! Shrink γ and 9
Only air moves from the wet well to the middle part 2.

Tens of seconds after the accident, most of the air in the dry well moves to the #1 wet well air barrier 2, and at this stage, the inside of the dry well is almost only water vapor. From this point on, only water vapor is released from the downcomer 6.

Under such conditions, when steam condenses at the tip of the downcomer 6, a lateral load is generated at the tip of the downcomer 6, and a large stress is generated at the joint between the downcomer 6 and the vent header 5.

Since this load is generated randomly in all horizontal directions, the stress applied to the joint between the downcomer 6 and the vent header 5 is applied in the longitudinal direction of the vent header 5 ( When the load is applied to the tip of the downcomer 6 at the arrow (1) in the figure, the value becomes the largest.

Also, the lateral load is simultaneously applied to both downcomers 6 in the longitudinal direction of the vent header 5 and in the 90° direction (arrow in the figure).
b)), a large torsional stress is generated in the vent header 5 (swing mode).

To cope with these loads, Wetwell II
A support structure that supports the downcomer 6t and downcomer 6t is considered, but due to thermal stress, support cannot be provided for the wet well Ill, and the vent pipe 4. Vent header 5. Downcomer 6
The current solution has been to increase the thickness of the plate, but this has resulted in many problems in terms of safety, economy, and manufacturing (depending on the plate thickness).

The object of the present invention is to provide a pent support structure tube suitable for reducing the bichral load applied to the downcomer during steam condensation and the swing mode load applied to the vent header.
The purpose is to improve safety, economy, and ease of production.

Currently, the structural bottleneck in dynamic loading of the containment vessel is the integrity of the downcomer against lateral loads.
The only solution was to increase the wall thickness. The present invention has recently investigated whether it is possible to support the wet well wall so that the load due to the swing mode is not affected by thermal stress on the wet well wall. A solution was found by supporting the fist through an auxiliary support rod. Furthermore, in order to create a support structure that is effective against all horizontal loads, the structure is designed to support in two or more directions.

Hereinafter, a series of embodiments of the present invention will be explained with reference to FIG.

An auxiliary support rod 9 is installed horizontally above the ring gutter 8 at the same water depth as the tip of the downcomer 6.

Angle (60
~90°St is optimal) At the same time, two support rods 10 are identified with a bottle 11. This bottle 11 is most suitable for releasing thermal stress, but even if it is fixed by # contact, the thermal stress can be released by the auxiliary support rod 9, so the effects of the present invention can be obtained.

A vent was created at the tip of the downcomer 6 due to steam condensation during the accident.
In the case where the lateral load in the longitudinal direction of the header 5 (as indicated by the arrow (→) in the figure) is applied, the downcomer 6 is
The vibration of the downcomer 6 is prevented, and the stress at the contact portion of the downcomer 6 with the vent header 5 is eliminated.

10,000, vent at the tip of downcomer 6 during steam condensation IIIA.
Even when a 2-chill load (swing mode load, arrow (b) in the figure) is applied in the direction perpendicular to the longitudinal direction of the header 5, the swing mode of both downcomers 6 connected by the placing 7, as in the above case, Mode is prevented by the two support rods 10, and the stress at the joint between the vent header 5 and the downcomer 6 and the twisting of the vent header are eliminated.

In addition, the temperature of the pool water increases due to the high temperature and high pressure reactor system released into the containment vessel in the event of an accident.
This causes the support rod 10 to stretch and apply force to the auxiliary support rod 9 from the lateral direction, but this force can be absorbed by the bending of the auxiliary support rod 9.

As described above, the force and displacement applied from the support rod 10 to the auxiliary support rod 9 are absorbed by the elasticity of the auxiliary support rod 9, and since the auxiliary support rod 9 is installed on the ring gutter 8, the wet well 1 wall There is no fist that directly applies local force to the fist.

Thereby, it is possible to effectively prevent the downcomer 6 from swinging due to the two-chill load 1 acting in all directions on the tip of the downcomer 6 during steam aim and the load during the swing mode.

According to the present invention, it is possible to absorb the displacement of the support structure and other structures due to temperature changes inside the containment vessel in the event of an accident, and even the electric charge applied to the support structure in the event of an accident can be directly imaged locally on the wet well wall. The downcomer can be supported without applying any electric charge, and the support structure method effectively prevents the downcomer from swinging due to lateral loads acting on the tip of the downcomer due to steam condensation during an accident and swing mode loads. Therefore, there is no need to make the wall thickness of the vent system excessively thick, and safety, economic efficiency, and ease of manufacturing can be improved.

[Brief explanation of the drawing]

M1 diagram (A) (to) is the acid 1li1T direction diagram of the wet well part of the conventional Mark-I type reactor containment vessel and A-A
[Figure 2 (A) (G) is the Mark-I according to the present invention.
Vertical section of wet well part of type reactor containment valley - and A
- A diagram, 3rd row (2) (2) and 4th row (2) (g) show the vertical w'r plane section and A-A view of the wet well part in an application example according to the present invention. 1... Wet well, 2... Wet well space, 3... Pool water, 4... Pen tube, 5... Vent header, 6... Downcomer, 7... Bu Racing, 8...Ring gutter, 9...Auxiliary support rod, 1
0...Support rod, respect 1 cause (A) i2<p,)! Figure 43 (A 4th error (c)

Claims (1)

[Claims] 1. Dry well, wet well, and vent pipe. A vent system support structure that supports the vicinity of the tip of the down cuff via an auxiliary support structure installed on a wet well ring gutter in a nuclear reactor containment vessel consisting of a vent header and a downcomer. 2. In the support structure that supports the vicinity of the tip of the downcomer, the support structure supports two horizontal directions (including the minute direction) so that movement of one downcomer in two or more horizontal directions can be restricted. The vent-based support structure according to item 1.